There is known a camera shutter which is capable of selection between a shutter opening operation by a spring and a shutter opening operation by a motor and which is capable of controlling the diaphragm and the shutter speed independently of each other depending on the photographing conditions. For example, there is a camera shutter in which the timing of the operation of a shutter opening member and the timing of operation of a shutter closing member are controlled by separate electro-magnets (see Japanese Unexamined Patent Publication No. H6-138515).
In contrast, the present applicant proposed a camera shutter having a structure such that the diaphragm is set to a predetermined value by causing a closing member to operate by a driving ring capable of turning clockwise and counterclockwise through a motor, and the lens opening is closed by the closing member after opening a shutter sector by an opening member, wherein when the driving member begins to operate from a first state, the operation of the opening member is restrained by an opening controlling portion of the driving ring and when the driving member begins to operate from a second state, the operation of the opening member is restrained by an opening restraining member. This is described in Japanese Unexamined Patent Publication No. H7-261239.
Of the above-described two known technologies, the former has had the problem that since it requires two electromagnets and spaces for setting these electromagnets and a power supply for energizing the electromagnets, it is not possible to obtain miniaturization and power savings.
On the other hand, it can be said that the latter technology has solved the problems of miniaturization and power savings since the provision of a single electromagnet can be used. However, this latter technology has also had the problem that when the release button is once pressed in a spring-drive mode, unless the operation of the camera up to the termination of photographing including exposure is performed, the shutter can not be returned to its initial state because the shifting from the spring-drive mode to the motor-drive mode can not be effected until the photographing operation in the spring-drive mode has been completed.